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This section presents the findings of gaps on existing VIM platforms. The focus
was to identify gaps based on the features and requirements specified in Section
3.3. The analysis work determined gaps that are presented here.

The interval for collection has to be set large enough which depends on
the size of the deployment and the number of metrics to be collected.

The interval may not be less than one second in even small deployments.
The default value is 60 seconds.

Alternative: OpenStack has a message bus to publish system events.
The operator can allow the user to connect this, but there are no
functions to filter out other events that should not be passed to the user
or which were not requested by the user.

Only the owner of virtual resource hosted by target physical resource
can receive the notification that can trigger some process for
applications which are running on the virtual resource (e.g. cut off
VM).

OpenStack offers a telemetry service, Ceilometer, for collecting measurements of
the utilization of physical and virtual resources [CEIL]. Ceilometer can
collect a number of metrics across multiple OpenStack components and watch for
variations and trigger alarms based upon the collected data.

OpenStack Nova [NOVA] is a mature and widely known and used component in
OpenStack cloud deployments. It is the main part of an
“infrastructure-as-a-service” system providing a cloud computing fabric
controller, supporting a wide diversity of virtualization and container
technologies.

Nova has proven throughout these past years to be highly available and
fault-tolerant. Featuring its own API, it also provides a compatibility API with
Amazon EC2 APIs.

When maintenance mode for a compute host is set, trigger VM evacuation to
available compute nodes before bringing the host down for maintenance.

As-is

If setting a compute node to a maintenance mode, OpenStack only schedules
evacuation of all VMs to available compute nodes if in-maintenance compute
node runs the XenAPI and VMware ESX hypervisors. Other hypervisors (e.g.
KVM) are not supported and, hence, guest VMs will likely stop running due
to maintenance actions administrator may perform (e.g. hardware upgrades,
OS updates).

Gap

Nova libvirt hypervisor driver does not implement automatic guest VMs
evacuation when compute nodes are set to maintenance mode ($novahost-update--maintenanceenable<hostname>).

Monasca is an open-source monitoring-as-a-service (MONaaS) solution that
integrates with OpenStack. Even though it is still in its early days, it is the
interest of the community that the platform be multi-tenant, highly scalable,
performant and fault-tolerant. It provides a streaming alarm engine, a
notification engine, and a northbound REST API users can use to interact with
Monasca. Hundreds of thousands of metrics per second can be processed
[MONA].

Zabbix is an open-source solution for monitoring availability and performance of
infrastructure components (i.e. servers and network devices), as well as
applications [ZABB]. It can be customized for use with OpenStack. It is a
mature tool and has been proven to be able to scale to large systems with
100,000s of devices.